[Digestion] DOC Biogas potential

[alastair ward (IGER-NW)]

I agree with David that a digester is the best way to find the methane
potential, but this raises a question that has bothered me about the BMP
assays in the past: The method uses a nutrient and trace element mixture
to support the microbes, but if a feedstock is deficient in one or more
of these, the BMP assay will not take this into account. If something is
missing in the feed then I would like this to be reflected in the
results. Does anybody know why the assay uses these additives?

Regards,

Alastair Ward


-----Original Message-----
From: digestion-bounces at listserv.repp.org
[mailto:digestion-bounces at listserv.repp.org] On Behalf Of David Fulford
Sent: 17 August 2006 09:30
To: Arjun Gupta; digestion at listserv.repp.org
Subject: Re: [Digestion] DOC Biogas potential


Arjun Gupta and listers,

The experiences of Vivekananda Kendra - NARDEP in southern Tamil Nadu
and 
also Dr Karve of ARTI in Pune (see 
http://www.ashdenawards.org/technical_summary06_india_vk_nardep and 
http://www.ashdenawards.org/technical_summary06_india_arti) show that 
deoiled cake of all oil seeds (including castor) is a very good feed for

biogas plants. The biogas production is very much higher than that for 
cattle dung (Dr Karve claims 40 times).

The best way to test the biogas potential of a feedstock is to put it
into 
a small biogas plant. The ARTI design is very cheap and mobile (made
from 
two spun HPDE plastic water tanks), so would be an ideal test bed. My
own 
experience of testing feedstock samples is that the standard batch 
digestion tests do not give the same results as using a semi-continuous 
process. A well-adapted semi-continuous plant is surprisingly robust and

can cope with a wide range of feedstocks and a wide range of dilutions
and 
total solid content. Obviously, if there is too much water, it just
washes 
out the bacteria, so you need to use a UASB or anaerobic filter, which
are 
designed to clean up polluted water. The upper limit for total solid 
content, though, seems very high and is usually constrained by the
desire 
to pour the feedstock in and out of the plant. Mix a known amount of
the 
feed to be tested with the regular feed of the plant (cow dung, food 
wastes) and use it for several days and measure the increase in gas 
production over the quantity measured when the plant is fed steadily
with 
the standard feed.

regards,

David Fulford

At 10:20 17/08/2006 +0530, Arjun Gupta wrote:
>Hello,
>    Has anyone experienecd using Castor De-oiled cake to produce 
>biogas. Also what are the basic analysis tests to be done on a 
>potential biogas feed stock to determine it's biogas potential, 
>dilution and solids in output slurry percentage. How does one use these

>figures. Thankyou. _______________________________________________
>Digestion mailing list
>Digestion at listserv.repp.org
>http://listserv.repp.org/mailman/listinfo/digestion_listserv.repp.org

*** Dr David Fulford, Energy Group, Engineering Building       ***
***     School of Construction Management and Engineering      ***
***      The University of Reading, Whiteknights,              ***
***    Reading RG6 6AY, UK      Tel: +44-(0)118-378 8563,      ***
*** Fax: +44-(0)118-931 3327 E-mail: D.J.Fulford at Reading.ac.uk ***  


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